Systems superficially similar to the present invention have heretofore been made and sold. Such prior art devices, however, have suffered difficulties in the fact that tensile forces on leads extending from a unit housing electrical components have been applied directly to the components rather than being positively shielded therefrom. The present invention is an improvement over prior art systems in providing structure which mechanically invades electrical insulation of leads to transfer tensile forces from the leads to the housing of the components rather than to the components themselves.